There are a number of magnetic catches and closures on the market. The simplest of these are magnets for holding swing doors closed. Such catches are often deployed on kitchen cabinets and the like.
Magnets may also be used, like a spring, to resist the closure of a door or catch. Since magnets are polar, by deploying magnets on a pair of surfaces, the surfaces can be made to attract or repel each other.
EP2436280 to Fiedler Joachim, titled “Mechanical-magnetic connection structure” describes a closure consisting of connecting modules for connecting two elements, and comprising tubular or grooved guide sections, which are configured to be inserted into one another. Permanent magnets are arranged on a base of the guide sections, where the guide sections made of ferromagnetic materials exhibit circular cross section. One permanent magnet is fixed in one of the guide sections, and another permanent magnet is arranged to moved in a such a manner that the latter magnet automatically self-aligns in a pulling position in relation to former magnet when the closure is closed. It appears that in the described and claimed devices, a resistive force is provided by a spring. The specification states that the term spring is not to be taken as necessarily meaning a helical spring, and may be a springy foam, for example. The term does, however, relate to a mechanical, Hookian element, and not to a magnet.
U.S. Pat. No. 7,889,036 to Fiedler Joachim describes a “Magnetic Holding Device” which relates to a universally-applicable, detachable magnetic catch, suitable, for example, for the closing and opening of containers of for fixing or releasing an object, whereby each magnet is held with a positive fit in the recess of a holder. One of said holders may be displaced by means of an operating device such that the magnetic poles of the magnets oppose each other to be either attracting or repelling. Each magnet has an upper side, an underside, parallel to the above and a circumferential surface at an angle of 90 to the upper and underside. The upperside and the underside of the magnet are a non-symmetrical planar surface and the recess of the holder has a horizontal cross-sectional surface, identical to the non-symmetrical form of the upperside and the underside such that the magnet may only be introduced into the corresponding recess with the poles in a functional alignment. Thus U.S. Pat. No. 7,889,036 describes a mechanic flap that is lockable by oppositely aligned magnets N-S S-N, which can be brought into alignment N-N S-S to release.
The locking force is purely magnetic. Thus once the magnets are overcome the lock may be opened. There is no mechanical safety catch of any sort.
WO2005094625 (U.S. Pat. No. 8,009,002) titled “Detachable Magnet Holder” also to Fiedler Joachim relates to a universally applicable detachable magnet holder with a fixed magnet and an opposite-lying magnet which can rotate about a point of rotation and which is provided with magnet pole surfaces, wherein each magnet pole surface comprises at least two poles which, when closed, attract each other and which, when open, repel each other once the rotatable magnet has been rotated by means of an actuation device. According to the invention, a distance element made of a non-ferromagnetic material, is fixed to one of the magnet pole surfaces, whereby the bearing surface on the opposite magnet pole surface is a maximum ⅓ of the surface and a centering engaging device (10a, 10b, 11) is arranged in the vicinity of the magnet poles in order to receive magnetic sheer forces.
The magnets provide the locking force. The magnets are rotated. US2012044031 to Ninomiya Tomoyasu titled ‘Magnetic Connector describes a magnetic connecting device, which is easily separated without both hands but one that is not easily separated in a direction in which a pulling force is applied, is disclosed. Each of a pair of coupling pieces is respectively provided with each of a pair of coupling piece main bodies including joint surfaces capable of joining each other. At least one magnet piece is embedded in each of the joint surfaces such that the coupling piece main bodies attract to join each other. An attaching piece for attaching a string body is provided on each of the coupling pieces, and is provided with a slide guide structure formed on a side of the joint surface of each of the coupling piece main bodies for slidingly guiding the other in a predetermined direction with respect thereto.
This application is directed to jewellery and the like. The two sides of the couple have string holders—i.e. loops for engaging straps or belts. There are magnets for holding the elements together but also a mechanical dovetail or mortis to take the strain.
The concept of sliding to release, to align N-N S-S or at least to displace a N-S and align a second magnet is discussed. The strain to be overcome by the catch is in plane rather than tangential thereto. The two parts are twisted apart.
U.S. Pat. No. 5,367,891 to Furuyama Kazuo, titled “Fitting Device for Accessory” describes a fitting device for an ornamental accessory that is made up of a pair of connecting members each having a cylindrical portion on an end to be fitted together in a rotatable manner relative to each other. One of the connecting members has at its fitting end at least one piece of guide grooves formed in series. The guide groove is made up of a thrust groove which is open into an outside and extends in an axial direction of the connecting member, a rotation groove which bends from an inner end of the thrust groove and extends in a circumferential direction, and a fixing groove which bends from that end of the rotation groove which is away from the thrust groove towards the fitting end. The other of the connecting members has at its fitting end a projection which is thrusted into the thrust groove and moves along the rotation groove. The projection is positioned to correspond to the guide groove. Each of the connecting members has inside its fitting end portion magnet pieces disposed on a plane. The magnet pieces have N pole and S pole arranged to lie alternately in a circumferential direction to form magnetized surfaces facing outwards. This patent is directed to a bayonet clip for a necklace or similar, with a four way magnetic head to help alignment and to provide extra security.
U.S. Pat. No. 6,640,398 to Hoffman Leslie C titled “Magnetic Clasp for Jewelry” relates to magnetic clasps for securing the opposed ends of chains and other jewelry. Each clasp includes an arrangement for securing separable bodies by means of magnets that have been poled to present opposed surfaces of opposite magnetic polarities. In a first embodiment, disk-like magnets are received in channels of mating elongated body members of like configuration. End flanges of the elongated body members, in addition to the disk-like magnets, provide axial resistance to separation while the resultant magnetic force prevents separation in the transverse direction. In a second embodiment, disk-like magnets of divided polarities are seated at ends of mating bodies. A pin-and-slot locking mechanism is formed in the two bodies and the magnets are oriented relative thereto so that resultant repulsive magnetic forces force the two magnets into mating alignment when in the longitudinal slot for maximum magnetic holding force. In a third embodiment, magnetic disks are held side-by-side by holders within a split hemispherical housing.
Despite the wide range of magnetic and mechanical fastenings, there is a need for specialist fastenings with unique features.